zap vs zerolog
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
A fast Go logging library that writes structured JSON with almost no memory allocation.
The short answer
Choose zap if you need…
- Go developers building services that log heavily
- Teams that want structured, machine-readable log output
- Projects where logging overhead in hot code paths is a concern
- Developers who want a choice between typed and loosely typed logging APIs
Choose zerolog if you need…
- Go developers who want machine-readable JSON logs
- Backend services where logging overhead matters
- Teams that log structured fields and send logs to log-processing tools
- Developers who want a chained, typed logging API
Side-by-side
| zap | zerolog | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 24.7k | 12.5k |
| Setup difficulty | Beginner | Beginner |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | Go | Go |
| Last code update | 51 days ago | 23 days ago |
What each one is
zap
Zap is a logging library for the Go programming language. It writes log messages with levels (such as info or error) and attached key-value details, so logs are easy to search and analyze. Developers use it in server code where logging speed matters, and it offers two APIs: a faster strongly typed one and a looser, more convenient one.
zerolog
Zerolog is a logging library for the Go programming language. It records events as structured JSON (or optionally CBOR), where each message can carry typed key-value fields such as strings, numbers, and errors. It is built to avoid allocations and reflection, which the README says keeps it fast and light on memory.
Best for
zap
- Go developers building services that log heavily
- Teams that want structured, machine-readable log output
- Projects where logging overhead in hot code paths is a concern
- Developers who want a choice between typed and loosely typed logging APIs
zerolog
- Go developers who want machine-readable JSON logs
- Backend services where logging overhead matters
- Teams that log structured fields and send logs to log-processing tools
- Developers who want a chained, typed logging API
Strengths
zap
- The README reports strong benchmark results against several other Go logging packages, with the caveat that benchmarks should be taken with a grain of salt
- Offers both a strongly typed Logger and a looser SugaredLogger so you can choose the trade-off
- Stable API with a stated commitment to no breaking changes in the 1.x series
zerolog
- Designed for low or zero allocation, per the README benchmarks section
- Strongly typed fields and a simple chaining API
- Supports leveled logging, sampling, hooks, and log/slog integration
Not ideal for
zap
- Non-Go projects, since it is only for Go (reason: it is a Go library)
- Beginners who only need simple print statements (reason: setup and typed fields add concepts to learn)
- Projects that must use only the standard library's log/slog (reason: zap is a separate dependency with its own API)
zerolog
- People who want readable colored console output by default: the README says pretty printing via ConsoleWriter is available but inefficient
- Non-Go projects, since it is a Go package
- Beginners who need a full logging framework with rotation or file management, which the README does not describe
Trade-offs
zap
- Only supports the two most recent minor versions of Go, according to the README
- Typed Logger API requires more verbose code than the SugaredLogger
- Performance claims come from the project's own benchmark suite, so independent results may differ
zerolog
- Chained calls silently do nothing unless Msg or Msgf is called, and the compiler will not warn you
- By default it writes every level, including trace, to stderr until SetGlobalLevel is called
- Pretty console output is available but slower, as the README notes
Getting started
zerolog
Install the global logger package
go get -u github.com/rs/zerolog/logFrequently asked questions
What is the difference between zap and zerolog?
zap: A fast, structured logging library for Go programs. zerolog: A fast Go logging library that writes structured JSON with almost no memory allocation. zap suits go developers building services that log heavily, while zerolog suits go developers who want machine-readable json logs.
Are zap and zerolog free?
zap: Free and open source. zerolog: Free and open source.
Is zap or zerolog more popular?
zap has more GitHub stars (24.7k) than zerolog (12.5k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to zap and zerolog?
Other options people compare them with include Logrus.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.